Fluid compressor

ABSTRACT

A fluid compressor  1  comprises a rotation shaft  300  having a compression mechanism  2  and an oil passage  311 , a motor  600 , bearings  401  and  803 , and a centrifugal pump part  900  for supplying oil through the oil passage  311 . The rotation shaft  300  integrally comprises a main shaft portion  302 , a crank pin  301  eccentrically provided to the main shaft portion  302 , and a sub-bearing supported portion  303  having a smaller diameter than the main shaft portion  302 . The oil passage  311  has a first oil passage  311   a  extending from a lower end of the sub-bearing supported portion  303  to a lower portion of the main shaft portion  302 , and a second oil passage  311   b  that is communicated with the first oil passage  311   a  and extends to an upper end of the crank pin  301 . The second oil passage  311   b  comprises a passage portion that has a smaller diameter than and is placed at an outer of the first oil passage  311   a , a plurality of the second oil passages  311   b  are provided within a plain of said crank pin  311.

BACKGROUND OF THE INVENTION

The present invention relates to a fluid compressor comprising a rotation shaft having an oil passage, and particularly to the one suitably used as a coolant compressor for cooling or air conditioning, or a fluid compressor for air or the like.

A conventional fluid compressor is disclosed, for example, in JP-A-2001-349291. A scroll compressor shown in FIG. 1 of JP-A-2001-349291 comprises in its sealed container, a compression mechanism for compressing fluid, a rotation shaft connected to the compression mechanism and having an oil passage, a motor for driving the rotation shaft, a main bearing for supporting the rotation shaft above the motor, a sub-bearing for supporting the rotation shaft below the motor, and a positive displacement pump part for supplying oil reserved in the bottom of the sealed container through the oil passage to the compression mechanism and the bearings.

The rotation shaft integrally comprises a main shaft portion fixed to a rotor of the motor, a crank portion eccentrically provided at the upper end of the main shaft portion and connected to the compression mechanism, and a small-diameter, sub-bearing supported portion provided at the lower end of the main shaft portion and supported by the sub-bearing. Note that the small diameter of the sub-bearing supported portion of the rotation shaft allows the sub-bearing to precisely bear the sub-bearing supported portion. The oil passage of the rotation shaft is a small-diameter hole that extends from the lower end of the sub-bearing supported portion to the upper end of the crank portion and is concentrically provided with the rotation shaft.

A conventional fluid compressor is disclosed, for example, in JP-A-2-245492. A scroll compressor shown in FIGS. 1 to 3 of JP-A-2-245492 comprises in its sealed container, a compression mechanism for compressing fluid, a rotation shaft connected to the compression mechanism and having an oil passage, a motor for driving the rotation shaft, an upper main bearing portion for supporting the rotation shaft, and a centrifugal pump part (cap) for supplying oil reserved in the bottom of the sealed container through the oil passage to the compression mechanism and the bearings.

The rotation shaft integrally comprises a main shaft portion fixed to a rotor of the motor, a crank pin eccentrically provided at the upper end of the main shaft portion and connected to the compression mechanism, and a portion provided at the lower end of the main shaft portion with the same diameter and projecting downward below the motor. The oil passage of the rotation shaft includes a first oil passage extending upward from the lower end and a second oil passage of a small diameter that is communicated with the first oil passage in a plain thereof and extends to the upper end of the crank pin.

BRIEF SUMMARY OF THE INVENTION

Generally, it is desirable that the oil passage through the main shaft portion has a small diameter to ensure the strength of the main shaft portion of the rotation shaft.

In the case of the scroll compressor of JP-A-2001-349291 where the oil passage of the rotation shaft is a small-diameter hole that extends from the lower end of the sub-bearing supported portion to the upper end of the crank portion and is provided concentrically with the rotation shaft, the expected centrifugal force on the oil with the oil passage is not so substantial. Accordingly, JP-A-2001-349291 employs the positive displacement pump part to ensure the amount of oil supply. However, the positive displacement pump part generally has a disadvantage of its expensiveness compared to centrifugal pump parts.

The scroll compressor of JP-A-2-245492 employs the centrifugal pump part thereby having an inexpensive structure. However, it presents a problem in ensuring a substantial amount of oil supply since the second oil passage is communicated with the first oil passage in a plain thereof and there is provided only one second oil passage. Another problem is that a raised temperature of oil makes it difficult to ensure the required amount of oil supply since it lowers the viscosity of the oil and thus lowers the centrifugal effect acting on the inner wall in the centrifugal pump part.

It is an object of the present invention to provide a fluid compressor that has an inexpensive structure, ensures a substantial amount of oil supply, and is excellent in reliability.

To achieve the above object, the present invention provides a fluid compressor comprising in a sealed container: a compression mechanism for compressing fluid; a rotation shaft connected to the above described compression mechanism and having an oil passage; a motor for driving the above described rotation shaft; a main bearing for supporting the above described rotation shaft above the above described motor; a sub-bearing for supporting the above described rotation shaft below the above described motor; and a centrifugal pump part for supplying oil reserved in a bottom of the above described sealed container through the above described oil passage to the above described compression mechanism and the above described bearings, wherein the above described rotation shaft integrally comprises a main shaft portion fixed to a rotor of the above described motor, a crank pin eccentrically provided at an upper end of the above described main shaft portion and connected to the above described compression mechanism, and a small-diameter, sub-bearing supported portion provided at a lower end of the above described main shaft portion and supported by the above described sub-bearing; the above described oil passage of the above described rotation shaft comprises a first oil passage extending from a lower end of the above described sub-bearing supported portion to a lower portion of the above described main shaft portion, and a second oil passage that is communicated with the above described first oil passage and extends to an upper end of the above described crank pin; and the above described second oil passage comprises a passage portion that has a smaller diameter than and is placed at an outer of the above described first oil passage; a plurality of the above described second oil passages are provided within a plain of the above described crank pin.

According to the present invention, a fluid compressor is provided that has an inexpensive structure, ensures a substantial amount of oil supply, and is excellent in reliability.

Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a longitudinal section view of a scroll compressor according to a first embodiment of the present invention;

FIG. 2A is a longitudinal section view of a lower portion of a rotation shaft and a pump part of the scroll compressor of FIG. 1;

FIG. 2B is a section view taken along IIB-IIB in FIG. 2A;

FIG. 3A is a top view of a pump member used in a scroll compressor according to a second embodiment of the present invention;

FIG. 3B is a front view of a pump member used in a scroll compressor according to a second embodiment of the present invention;

FIG. 3C is a side view of a pump member used in a scroll compressor according to a second embodiment of the present invention;

FIG. 4 is a characteristic curve of a pump part according to a second embodiment;

FIG. 5A is a top view of a pump member used in a scroll compressor according to a third embodiment of the present invention;

FIG. 5B is a front view of a pump member used in a scroll compressor according to a third embodiment of the present invention;

FIG. 5C is a side view of a pump member used in a scroll compressor according to a third embodiment of the present invention;

FIG. 6A is a longitudinal section view of a pump part of a scroll compressor according to a fourth embodiment of the present invention;

FIG. 6B is a side view of a single pump blade of a scroll compressor according to a fourth embodiment of the present invention;

FIG. 6C is a section view taken along VIC-VIC in FIG. 6A;

FIG. 7A is a longitudinal section view of a pump part of a scroll compressor according to a fifth embodiment of the present invention;

FIG. 7B is a side view of a single pump blade of a scroll compressor according to a fifth embodiment of the present invention;

FIG. 7C is a section view taken along VIIC-VIIC in FIG. 7A;

FIG. 8A is a longitudinal section view of a pump part of a scroll compressor according to a sixth embodiment of the present invention;

FIG. 8B is a side view of a single pump blade of a scroll compressor according to a sixth embodiment of the present invention;

FIG. 8C is a section view taken along VIIIC-VIIIC in FIG. 8A;

FIG. 9A is a longitudinal section view of a pump part of a scroll compressor according to a seventh embodiment of the present invention;

FIG. 9B is a side view of a single pump blade of a scroll compressor according to a seventh embodiment of the present invention;

FIG. 9C is a section view taken along IXC-IXC in FIG. 9A;

FIG. 10A is a longitudinal section view of a lower portion of a rotation shaft of a scroll compressor according to an eighth embodiment of the present invention;

FIG. 10B is a section view taken along XB-XB in FIG. 10A;

FIG. 11A is a longitudinal section view of a lower portion of a rotation shaft of a scroll compressor according to a ninth embodiment of the present invention; and

FIG. 11B is a section view taken along XIB-XIB in FIG. 11A.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described with reference to drawings. Like reference numerals and characters in the drawings refers to like elements or equivalents.

A scroll compressor of a first embodiment of the present invention will be described with reference to FIG. 1, FIG. 2A and FIG. 2B. FIG. 1 is a longitudinal section view of a scroll compressor according to the first embodiment of the present invention. FIG. 2A is a longitudinal section view of a lower portion of a rotation shaft and a pump part of the scroll compressor of FIG. 1. FIG. 2B is a section view taken along IIB-IIB in FIG. 2A.

A scroll compressor 1 contains a compression mechanism 2 and a driving part 3 in a sealed container 700. In this embodiment, it is a vertical scroll compressor in which there are provided from upper to lower in order the compression mechanism 2, the driving part 3 and an oil reservoir 730, and the compression mechanism 2 and the driving part 3 are connected through a rotation shaft 300.

The compression mechanism 2 comprises as basic elements, a fixed scroll 100, a orbiting scroll 200 and a frame 400. The frame 400 is fixed to the sealed container 700 and constitutes a member for placing a roller bearing 401. The fixed scroll 100 comprises as basic elements, a base plate 101, a whirl lap 102, an intake inlet 103, and a discharge outlet 104 and is fixed to the frame 400 with a bolt 405. The lap 102 is vertically placed on one side of the base plate 101. The orbiting scroll 200 comprises as basic elements, a base plate 201, a whirl lap 202, a boss 203, and a backpressure hole. The lap 202 is vertically placed on one side of the base plate 201. The boss 203 is vertically projecting from the other side of the base plate 201 (opposite to the lap). Each element of the orbiting scroll 200 is formed by machining a mold consisting of a material such as cast iron or aluminum.

A compression chamber 130, in which the fixed scroll 100 and the orbiting scroll 200 are in engagement, performs compressing action such that its volume is reduced by the orbiting motion of the orbiting scroll 200. In this compressing action, the orbit movement of the orbiting scroll 200 causes working fluid to be taken into the compression chamber 130 through an intake tube 711 and the intake inlet 103. The taken working fluid, after a compression stroke, is discharged from the discharge outlet 104 of the fixed scroll 100 into the sealed container 700, then delivered through a discharge tube 701 and discharged from the sealed container 700. This maintains the pressure of the space within the sealed container 700 at a discharge pressure.

The sealed container 700 has an upper cap 710 and a lower cap 720. The upper cap 710 and the lower cap 720 are engaged over a center barrel of the sealed container. The edges of the engagement are welded by a welding torch that heats the edges with upward inclination and downward inclination. A leg 721 is attached to the bottom face of the sealed container 700.

On a side face of the sealed container 700 is provided a hermetic terminal 702 and a terminal cover 703 that allows power supply to a motor 600. The hermetic terminal 702 is disposed through the sealed container 700 and placed between an end coil of a stator 601 and the frame 400 while opposing a maximum diameter portion 407 a of a balance weight 407.

The discharge tube 701 is provided on a side face of the sealed container 700 opposite to the hermetic terminal 702 through the sealed container 700. The discharge tube 701 is placed between the end coil of the stator 601 and the frame 400 while opposing a maximum diameter portion 407 a of a balance weight 407.

The driving part 3 that drives the orbiting scroll 200 to orbit comprises as basic elements, the motor 600 having the stator 601 and a rotor 602, the rotation shaft 300, an Oldham coupling 500 which is a main component of a mechanism for preventing the rotation of the orbiting scroll 200, the frame 400, the roller bearings 401 and 803, and the boss 203.

The rotation shaft 300 integrally comprises a main shaft portion 302, a crank pin 301, and a sub-bearing supported portion 303. The roller bearings 401 and 803 constitute a rotation shaft supporting portion that rotatably is engaged to the main shaft portion 302 and the sub-bearing supported portion 303 of the rotation shaft 300. The boss 203 is provided to the orbiting scroll 200 such that the boss 203 is engaged to the crank pin 301 of the rotation shaft 300 movably in a thrust direction which is a direction of the rotation axis and rotatably.

The roller bearing 401 is placed above the motor 600. The roller bearing (sub-bearing) 803 that constitutes a main component of a sub-bearing part 800 is placed below the motor 600. A housing 802 is fixed by a bolt 805 to a lower frame 801 that is fixed to the sealed container 700. The roller bearing 803 is inserted into the housing 802 from upper side, and a housing cover 804 is also mounted over them from upper side.

A pump part 900 is provided at the lower end of the rotation shaft 300. The pump part 900 comprises a pump member 901 and a pump blade 902. The pump member 901 comprises a portion that is attached to the lower end of the rotation shaft 300, and a portion extending therefrom downward in which the section area of the fluid passage decreases. In other words, the pump member 901 comprises an upper cylindrical portion 901 a and a lower conical potion 901 b. The upper end of the upper cylindrical portion 901 a is inserted into and fixed to the lower end of the rotation shaft 300. An opening is provided at the lower end of the lower conical portion 901 b of the pump member 901. The pump blade 902 has an outer shape that is identical to an inner shape of the pump member 901, and is press-fitted in the pump member 901. That is, the pump blade 902 is provided to extend from an upper position in the pump member 901 to the opening at the lower end.

Thus, a structure is provided in which a centrifugal effect in the pump part 900 rotated with the rotation shaft 300 causes oil reserved in the oil reservoir 730 at the bottom of the sealed container 700 to be taken from the lower end of the pump part and then supplied into an oil passage 311 that is provided in the rotation shaft 300.

The oil passage 311 of the rotation shaft 300 comprises a first oil passage 311 a that extends from the lower end of the sub-bearing supported portion 303 to the lower part of the main shaft portion 302, and a second oil passage 311 b that is communicated with the first oil passage 311 a and extends to the upper end of the crank pin 301. The first oil passage 311 a is provided concentrically with the rotation shaft 300. The second oil passage 311 b has a passage portion that has a smaller diameter than and is placed at an outer of the first oil passage 311 a. There are provided a plurality of second oil passages 311 b (two in this embodiment) within the plain of the crank pin 301. The second oil passage 311 b overlaps the first oil passage 311 a so that the second oil passage 311 b is communicated with the first oil passage 311 a on the peripheral thereof in a substantial length in the axial direction. The second oil passage 311 b is placed at a position eccentric to the center axis of the rotation shaft 300. This eccentricity provides the action of a second centrifugal pump.

The Oldham coupling 500 is disposed on the back face of the base plate 201 of the orbiting scroll 200. Of two sets of keys that are provided to the Oldham coupling 500 and perpendicular to each other, one set slides in a key groove that is formed in the frame 400 and is a receiving portion for the Oldham coupling 500, while the other set slides in a key groove formed in the orbiting scroll lap 202 on its back face. Accordingly, the orbiting scroll 200 orbits with respect to the fixed scroll 100 without rotation in a plain vertical to the axial direction in which the scroll lap 202 is provided.

In the compression mechanism 2, when the rotation of the rotation shaft 300 connected to the motor 600 causes eccentric rotation of the crank pin 301, the orbiting scroll 200 performs orbiting motion with respect to the fixed scroll 100 while not performing the rotation because of the action of a mechanism for preventing the rotation of the Oldham coupling 500, and gas is then taken through the intake tube 711 and the intake inlet 103 into the compression chamber 130 that is formed of the scroll laps and 102 and 202. The orbiting motion of the orbiting scroll 200 causes the compression chamber 130 to move toward the center and its volume to be reduced to compress the gas, and the compressed gas is discharged from the discharge outlet 104 into a discharge chamber. The gas discharged into the discharge chamber is circulated around the compression mechanism 3 and the motor 600, and then discharged from the discharge tube 701 to the outside of the compressor.

The base plate 201 of the orbiting scroll 200 is provided with a backpressure hole through which the compression chamber 130 and a backpressure chamber 411 on the orbiting back face are communicated with each other, so that the pressure of the backpressure chamber 411 is maintained at a pressure between intake pressure and discharge pressure (i.e. intermediate pressure). The backpressure chamber 411 provided on the back face side of the orbiting scroll 200 is a space that is surrounded by the orbiting scroll 200, the frame 400 and the fixed scroll 100. Thus, the frame 400 is also a constituent member of the backpressure chamber 411.

A seal ring 410 provided at a groove 409 in the frame 400 prevents the flow of the discharged gas into the backpressure chamber 411. The orbiting scroll 200 is pressed against the fixed scroll 100 with the resultant force of the intermediate pressure in the backpressure chamber 411 and the discharge pressure acting on the internal side of the seal ring 410.

Here, the inside diameter of the seal ring 410 is smaller than the outside diameter of the roller bearing 401. To have this configuration, this embodiment is adapted so that the roller bearing 401 is inserted into the frame 400 from the rotation driving means side of the frame 400 and the inserted roller bearing 401 is fixed by a frame cover 403. A thrust bearing 402 is provided to the frame cover 403. The frame cover 403 is provided separately from the frame 400. The frame cover 403 is fixed to the frame 400 with the bolt 406. This bolt fixation ensures the sealing between the frame cover 403 and the frame 400 thereby preventing the oil leakage from the oil supply passage. Note that frame cover 403 comprises a portion that is inserted to the inside the frame 400 and pushes the roller bearing 401, and a portion that abuts the side face of the rotation driving means side of the frame 400 and is fixed thereto.

The balance weight 407 is provided to the rotation shaft 300 in the motor side with respect to the roller bearing 401. In this embodiment, the balance weight 407 is provided separately from the rotation shaft 300 and press-fitted to the rotation shaft 300 to be fixed thereto. However, the balance weight 407 may be provided integrally with the rotation shaft 300. The maximum diameter portion 407 a of the balance weight 407 is projecting from a peripheral face of the coil end of the stator 601, and has a larger diameter than the inside diameter of the coil end.

A balance weight cover 404 of metal that is formed in a cylinder shape, consisting of a bottom wall and a sidewall, is provided to cover the periphery of the maximum diameter portion 407 a of the balance weight 407. The balance weight cover 404 is also fixed to the frame 400, fastened along with the frame cover 403 with the bolt 406. The sidewall of the balance weight cover 404 is provided between the discharge tube 701 and the maximum diameter portion 407 a of the balance weight 407, and also between the hermetic terminal 702 and the maximum diameter portion 407 a of the balance weight 407.

Thus, the balance weight cover 404 confines the space between the frame 400 and the end face of the end coil of the stator 601. That is, outside space of the maximum diameter portion 407 a of the balance weight 407 is substantially confined by the balance weight cover 404.

Next, the oil supply passage will be described. When the rotation shaft 300 is rotated, the pump part 900 delivers oil in the oil reservoir 730 to the oil passage 311 in the rotation shaft. Part of the oil delivered to the oil passage 311 flows through the lateral hole 312 to the sub-bearing 803 (ball bearing), and then returns to the oil reservoir 730. The oil that has reached the upper portion of the crank pin 301 through the oil passage 311 passes a orbit bearing 210 and then flows to the roller bearing 401. Most of the oil that has lubricated the roller bearing 401 passes an oil discharge pipe 408 and returns to the oil reservoir 730. Part of the oil that has lubricated the roller bearing 401 passes the gap between the frame cover 403 and the rotation shaft 300, then reaches the balance weight 407, and is scattered by the balance weight 407. The scattered oil attaches to the interior surface of the side wall 404 b of the balance weight cover 404 to be recovered, and returns to the oil reservoir 730, for example, by flowing down to the motor 600.

On the peripheral face of the boss 203 of the orbiting scroll 200 is provided an oil supply pocket 205, which reciprocates between the inside and outside of the seal ring 410 with the orbiting motion of the orbiting scroll 200 so that part of oil between the orbit bearing 210 and the bearing 401 is delivered to the backpressure chamber 411. The delivered oil is supplied to the Oldham coupling 500, and then supplied to the sliding faces of a mirror plate face 105 of the fixed scroll and the base plate 201 of the orbiting scroll 200.

The oil delivered to the backpressure 411 flows through the backpressure hole or a narrow aperture in the mirror plate sliding face into the compression chamber 130. The oil that has flowed into the backpressure chamber 130 is discharged along with compressed coolant gas from the discharge outlet 104, then separated from the coolant gas in the sealed container 700, and returns to the oil reservoir 730.

According to this embodiment, the rotation shaft 300 integrally comprises the main shaft portion 302 fixed to the rotor 602 of the motor 600, the crank pin 301 eccentrically provided at the upper end of the main shaft portion 302 and connected to the compression mechanism 2, and the small-diameter, sub-bearing supported portion 303 provided at the lower end of the main shaft portion 302 and supported by the sub-bearing 803, so that the sub-bearing 803 precisely bears the sub-bearing supported portion 303 while ensuring the required strength for the rotation shaft 300.

Further, according to this embodiment, since the centrifugal pump part is used, it is possible to reduce the cost compared with the case of using a positive displacement pump part. Moreover, since the pump blade 902 extends to the lower end of the pump member 901, the capability of supplying oil is substantially maintained even when the amount of oil in the oil reservoir 730 decreased with the action of the centrifugal pump blade 902 extending to the lower end of the pump member 901, and therefore, a more reliable pump mechanism can be provided.

Further, according to this embodiment, the oil passage 311 of the rotation shaft 300 comprises the first oil passage 311 a that extends from the lower end of the sub-bearing supported portion 303 to the lower portion of the main shaft portion 302, and the second oil passage 311 b that is communicated with the first oil passage 311 a and extends to the upper end of the crank pin 301; the second oil passage 311 b has a passage portion that has a smaller diameter than the first oil passage 311 a and is placed at an outer of it; a plurality of such second oil passages 311 b are provided within the plain of the crank pin 301, thereby ensuring both a substantial centrifugal force and a substantial section area of the fluid passage within the limited section area of the rotation shaft 300 while the features of the rotation shaft 300 are satisfied. By means of it, the second oil passage 311 bacts as a second centrifugal pump, and the substantial amount of oil supply is ensured with an inexpensive structure, a reliable scroll compressor is achieved.

Next, second to ninth embodiments will be described with reference to FIG. 3A to FIG. 11B. The description will be made about the features which is different from the first embodiment, and the other features are substantially the same as those of the first embodiment.

A second embodiment will be described with reference to FIGS. 3A to FIG. 4. FIGS. 3A to 3C are diagrams for a pump member of a scroll compressor according to the second embodiment of the present invention: FIG. 3A is a top view; FIG. 3B is a front view; and FIG. 3C is a side view. FIG. 4 is a characteristic curve of a pump part according to a second embodiment.

In the second embodiment, a pump part 900 has only a pump member 901 as constituent member and no pump blade 902 as used in the first embodiment. The pump member 901 is generally in a conical shape in which the connecting portion with the rotation shaft 300 is in a cylindrical shape, and the portion opposite to the rotation shaft 300 is in a flat shape, with the connecting portion and the flat shape portion on the opposite end formed of smooth curves.

According to the second embodiment, since the centrifugal effect acts on the entire section area of the flat shape portion of the pump member 901, the capability of supplying oil existing in the pump member 901 is enhanced, thereby reducing the influence of the oil viscosity and achieving stable oil supply. Specifically, in the case of a merely conical pump member 901, the reduction in oil viscosity in raised temperature reduces the amount of oil supply dramatically as shown in characteristic curve (b) in FIG. 4. However, in the case of the pump member 901 in a flat shape according to the second embodiment, there is only small change in the amount of oil supply as shown in characteristic curve (a) in FIG. 4, thereby achieving stable oil supply.

Moreover, according to the second embodiment, since a stable amount of oil supply can be achieved as described above, the pump part 900 can be constituted of a single member, and thus can have an inexpensive structure.

Next, a third embodiment will be described with reference to FIGS. 5A to 5C. FIGS. 5A to 5C are diagrams for a pump member of a scroll compressor according to the third embodiment of the present invention: FIG. 5A is a top view; FIG. 5B is a front view; and FIG. 5C is a side view.

In the third embodiment, a pump member 901 is generally in a cylindrical shape in which the portion connected with the rotation shaft 300 is in a cylindrical shape, and the portion opposite to the rotation shaft 300 is in a flat shape. The pump member 901 according to the third embodiment, because of its generally cylindrical shape, can have an inexpensive structure.

Next, a fourth embodiment will be described with reference to FIGS. 6A to 6C. FIGS. 6A to 6C are diagrams for a pump part of a scroll compressor according to the fourth embodiment of the present invention: FIG. 6A is a longitudinal section view of a pump part; FIG. 6B is a side view of a single pump blade of the pump part; and FIG. 6C is a section view taken along VIC-VIC in FIG. 6A.

In the fourth embodiment, a projection 901 cis provided inside a pump member 901. A pump blade 902, which is placed inside the pump member 901 and rotates along with the pump member 901, is subject to inertia force of the fluid in the pump 901 driven by the rotation shaft 300 and thus subject to force opposite to the rotation direction of the rotation shaft 300. In order to resist the force acting on the pump blade 902 and opposing to the rotation direction, the projection 901 c is provided inside the pump member 901 that serves as a stopper against the pump blade 902. The projection 901 c provided to the pump member 901 securely supports the pump blade 902, so that the pump part 900 can have a simple, inexpensive structure and enhanced reliability. Note that the lower end of the pump blade 902 extends only to the cylindrical portion of the pump member 901, and the upper portion of the pump blade 902 extends into the oil passage 311.

Next, a fifth embodiment will be described with reference to FIGS. 7A to 7C. FIGS. 7A to 7C are diagrams for a pump part of a scroll compressor according to the fifth embodiment of the present invention: FIG. 7A is a longitudinal section view of a pump part; FIG. 7B is a side view of a single pump blade of the pomp part; and FIG. 7C is a section view taken along VIIC-VIIC in FIG. 7A.

In the fifth embodiment, a pair of projections 901 c is provided inside a pump member 901. There are provided two pairs of projections 901 c at two respective opposite positions. A pump blade 902 is placed so that both the ends thereof are sandwiched between respective pairs of projections 901 c. Thus the pump blade 902 is securely supported to supply oil when the rotation shaft 300 is rotated either in normal direction or in reverse direction.

Next, a sixth embodiment will be described with reference to FIGS. 8A to 8C. FIGS. 8A to 8C are diagrams for a pump part of a scroll compressor according to the sixth embodiment of the present invention: FIG. 8A is a longitudinal section view of a pump part; FIG. 8B is a side view of a single pump blade of the pomp part; and FIG. 8C is a section view taken along VIIIC-VIIIC in FIG. 8A.

The sixth embodiment is different from the fifth embodiment in that a pump blade 902 extends to the lower end of a pump member 901, but the other features of the sixth embodiment are the same as those of the fifth embodiment. According to the sixth embodiment, similar to the first embodiment, the capability of supplying oil is substantially maintained even when the amount of oil in the oil reservoir 730 decreased with the action of the centrifugal pump blade 902 extending to the lower end of the pump member 901, and therefore, a more reliable pump mechanism can be obtained.

Next, a seventh embodiment will be described with reference to FIGS. 9A to 9C. FIGS. 9A to 9C are diagrams for a pump part of a scroll compressor according to the seventh embodiment of the present invention: FIG. 9A is a longitudinal section view of a pump part; FIG. 9B is a side view of a single pump blade of the pomp part; and FIG. 9C is a section view taken along IXC-IXC in FIG. 9A.

The seventh embodiment is different from the sixth embodiment in that the portion of a pump member 901 opposite to the connecting portion thereof to the rotation shaft 300 has a spherical surface, but the other features of the seventh embodiment are the same as those of the sixth embodiment. According to the seventh embodiment, the inner wall of the pump member 900 has steeper slope with respect to the axis of the rotation shaft 300 than the case of conical shape or cylindrical shape, so as to enhance the centrifugal pump effect and achieve the capability of stable oil supply, and therefore a more reliable pump mechanism can be provided.

Next, an eighth embodiment will be described with reference to FIG. 10A and FIG. 10B. FIG. 10A and FIG. 10B are diagrams for a lower portion of a rotation shaft of a scroll compressor according to an eighth embodiment of the present invention: FIG. 10A is a longitudinal section view of a lower portion of a rotation shaft; and FIG. 10B is a section view taken along XB-XB in FIG. 10A.

In the eighth embodiment, a pump member 901 has a periphery portion consisting of double cylinders. The outer space in the pump member 901 is open to the lower face of the sub-bearing part 800. The inner space in the pump member 901 is similar to that of the first embodiment.

According to the eighth embodiment, the cylindrical portion disposed at the periphery of the pump member 901 provides a third centrifugal pump effect. Oil discharged from the upper end of the third centrifugal pump is used for lubricating the sub-bearing 803 placed in the sub-bearing part 800. Therefore, stable oil supply to the sub-bearing 803 can be achieved, and since the oil supply passage is separated from the oil supply into the pump member 901, an oil supply structure can be obtained that is easily designed and has a higher reliability.

Next, a ninth embodiment will be described with reference to FIG. 11A and FIG. 11B. FIG. 11A and FIG. 11B are diagrams for a lower portion of a rotation shaft of a scroll compressor according to a ninth embodiment of the present invention: FIG. 11A is a longitudinal section view of a lower portion of a rotation shaft; and FIG. 11B is a section view taken along XIB-XIB in FIG. 11A.

In the ninth embodiment, means for connecting a pump member 901 to a rotation shaft 300 is a thread having a screw thread whose screw direction is the same as the rotation direction of the rotation shaft 300. The pump member 901 is subject to force opposite to the rotation direction of the rotation shaft 300. Accordingly, the thread of the connection means is subject to force in the direction for tightening the screw, due to the force opposite to the rotation direction of the rotation shaft 300 that acts on the pump member 901, and therefore the pump member 901 is not disconnected from the rotation shaft 300, and a more reliable pump structure can be obtained.

It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims. 

1. A fluid compressor comprising in a sealed container: a compression mechanism for compressing fluid; a rotation shaft connected to said compression mechanism and having an oil passage; a motor for driving said rotation shaft; a main bearing for supporting said rotation shaft above said motor; a sub-bearing for supporting said rotation shaft below said motor; and a centrifugal pump part for supplying oil reserved in a bottom of said sealed container through said oil passage to said compression mechanism and said bearings, wherein said rotation shaft integrally comprises a main shaft portion fixed to a rotor of said motor, a crank pin eccentrically provided at an upper end of said main shaft portion and connected to said compression mechanism, and a small-diameter, sub-bearing supported portion provided at a lower end of said main shaft portion and supported by said sub-bearing; said oil passage of said rotation shaft comprises a first oil passage extending from a lower end of said sub-bearing supported portion to a lower portion of said main shaft portion, and a second oil passage that is communicated with said first oil passage and extends to an upper end of said crank pin; and said second oil passage comprises a passage portion that has a smaller diameter than and is placed at an outer of said first oil passage; a plurality of said second oil passages are provided within a plain of said crank pin.
 2. The fluid compressor according to claim 1, wherein said first oil passage is provided concentrically with said rotation shaft, and said second passage overlaps said first oil passage so that said second oil passage is communicated with said first oil passage on a peripheral thereof in a substantial length in an axial direction.
 3. The fluid compressor according to claim 1, wherein said pump part comprises a pump member in a cylindrical shape attached to the lower end of said rotation shaft, and a pump blade placed inside said pump member; said pump member comprises a portion that is attached to the lower end of said rotation shaft, and a portion extending therefrom downward in which the section area of the fluid passage decreases; and said pump blade has an outer shape that is identical to an inner shape of said pump member, and is press-fitted in said pump member so as to reach a lower end of the inside of said pump member.
 4. The fluid compressor according to claim 3, wherein the portion of said pump member in which the section area of the fluid passage decreases has a spherical shape. 5 The fluid compressor according to claim 1, wherein said pump part comprises a cylindrical pump member, and said pump member has a cylindrical connecting portion to said rotation shaft and a flat portion opposite to said connecting portion.
 6. The fluid compressor according to claim 1, wherein said pump member comprises a cylindrical pump member attached to the lower end of said rotation shaft, and a pump blade placed inside said pump member; and the pump member has a projection for preventing rotation of said pump blade.
 7. The fluid compressor according to claim 1, wherein said pump part comprises a cylindrical pump member, and projections of said pump member are configured to sandwich a pump blade.
 8. The fluid compressor according to claim 1, wherein said pump part comprises a cylindrical pump member, and said pump member has a connecting portion to said rotation shaft that is connected by a thread having a screw thread whose screw direction is the same as the rotation direction of said rotation shaft.
 9. A fluid compressor comprising in a sealed container: a compression mechanism for compressing fluid; a rotation shaft connected to said compression mechanism and having an oil passage; a motor for driving said rotation shaft; a bearing for supporting said rotation shaft; and a centrifugal pump part for supplying oil reserved in a bottom of said sealed container through said oil passage to said compression mechanism and said bearings, wherein said pump part comprises a cylindrical pump member, and said pump member has a cylindrical connecting portion to said rotation shaft and a flat portion opposite to said connecting portion.
 10. A fluid compressor comprising in a sealed container: a compression mechanism for compressing fluid; a rotation shaft connected to said compression mechanism and having an oil passage; a motor for driving said rotation shaft; a main bearing for supporting said rotation shaft above said motor; a sub-bearing for supporting said rotation shaft below said motor; and a centrifugal pump part for supplying oil reserved in a bottom of said sealed container through said oil passage to said compression mechanism and said bearings, wherein said pump part comprises a double cylindrical pump member, and the outer space in said pump member is open to a lower face of said sub-bearing. 